---
layout: docs
page_title: Telemetry
description: >
  Overview of runtime metrics available in the Nomad Autoscaler.
---

# Nomad Autoscaler Telemetry

The Nomad Autoscaler agent collects various runtime metrics about the performance
of different libraries and subsystems. These metrics are aggregated on a ten
second interval and are retained for one minute. To configure the telemetry output
please see the [agent configuration][agent_telemetry_config].

This data can be accessed via the `/v1/metrics` HTTP endpoint, via sending a
signal to the Nomad Autoscaler process or via a number of integrations.

To view this data via sending a signal to the Nomad Autoscaler process: on Unix,
this is `USR1` while on Windows it is `BREAK`. Once Nomad Autoscaler receives
the signal, it will dump the current telemetry information to the agent's `stderr`.

This telemetry information can be used for debugging or otherwise
getting a better view of what Nomad is doing.

Below is sample output of a telemetry dump:

```text
[2020-08-25 10:01:20 +0100 BST][G] 'nomad-autoscaler.pathfinder.runtime.sys_bytes': 74793216.000
[2020-08-25 10:01:20 +0100 BST][G] 'nomad-autoscaler.pathfinder.runtime.malloc_count': 219856.000
[2020-08-25 10:01:20 +0100 BST][G] 'nomad-autoscaler.pathfinder.runtime.free_count': 183613.000
[2020-08-25 10:01:20 +0100 BST][G] 'nomad-autoscaler.pathfinder.runtime.total_gc_pause_ns': 348822.000
[2020-08-25 10:01:20 +0100 BST][G] 'nomad-autoscaler.pathfinder.runtime.total_gc_runs': 5.000
[2020-08-25 10:01:20 +0100 BST][G] 'nomad-autoscaler.pathfinder.runtime.num_goroutines': 12.000
[2020-08-25 10:01:20 +0100 BST][G] 'nomad-autoscaler.pathfinder.policy.total_num': 0.000
[2020-08-25 10:01:20 +0100 BST][G] 'nomad-autoscaler.pathfinder.runtime.alloc_bytes': 4316568.000
[2020-08-25 10:01:20 +0100 BST][G] 'nomad-autoscaler.pathfinder.runtime.heap_objects': 36243.000
[2020-08-25 10:01:20 +0100 BST][S] 'nomad-autoscaler.runtime.gc_pause_ns': Count: 5 Min: 38083.000 Mean: 69764.400 Max: 122291.000 Stddev: 31487.808 Sum: 348822.000 LastUpdated: 2020-08-25 10:01:26.574809 +0100 BST m=+1.241576679
[2020-08-25 10:01:30 +0100 BST][G] 'nomad-autoscaler.pathfinder.runtime.alloc_bytes': 4370504.000
[2020-08-25 10:01:30 +0100 BST][G] 'nomad-autoscaler.pathfinder.runtime.malloc_count': 220853.000
[2020-08-25 10:01:30 +0100 BST][G] 'nomad-autoscaler.pathfinder.runtime.free_count': 183613.000
[2020-08-25 10:01:30 +0100 BST][G] 'nomad-autoscaler.pathfinder.policy.total_num': 0.000
[2020-08-25 10:01:30 +0100 BST][G] 'nomad-autoscaler.pathfinder.runtime.num_goroutines': 12.000
[2020-08-25 10:01:30 +0100 BST][G] 'nomad-autoscaler.pathfinder.runtime.total_gc_pause_ns': 348822.000
[2020-08-25 10:01:30 +0100 BST][G] 'nomad-autoscaler.pathfinder.runtime.total_gc_runs': 5.000
[2020-08-25 10:01:30 +0100 BST][G] 'nomad-autoscaler.pathfinder.runtime.sys_bytes': 74793216.000
[2020-08-25 10:01:30 +0100 BST][G] 'nomad-autoscaler.pathfinder.runtime.heap_objects': 37240.000
```

## Runtime Metrics

The runtime metrics help understand the Nomad Autoscaler agent's memory and load
pressure performance.

<table>
  <thead>
    <tr>
      <th>Metric</th>
      <th>Description</th>
      <th>Type</th>
    </tr>
  </thead>
  <tbody>
    <tr>
      <td>
        <code>nomad-autoscaler.runtime.num_goroutines</code>
      </td>
      <td>Number of running goroutines</td>
      <td>Gauge</td>
    </tr>
    <tr>
      <td>
        <code>nomad-autoscaler.runtime.alloc_bytes</code>
      </td>
      <td>The number of allocated heap bytes</td>
      <td>Gauge</td>
    </tr>
    <tr>
      <td>
        <code>nomad-autoscaler.runtime.sys_bytes</code>
      </td>
      <td>The total bytes of memory obtained from the OS</td>
      <td>Gauge</td>
    </tr>
    <tr>
      <td>
        <code>nomad-autoscaler.runtime.malloc_count</code>
      </td>
      <td>Cumulative count of heap objects allocated</td>
      <td>Gauge</td>
    </tr>
    <tr>
      <td>
        <code>nomad-autoscaler.runtime.free_count</code>
      </td>
      <td>Cumulative count of heap objects freed</td>
      <td>Gauge</td>
    </tr>
    <tr>
      <td>
        <code>nomad-autoscaler.runtime.heap_objects</code>
      </td>
      <td>Number of allocated heap objects</td>
      <td>Gauge</td>
    </tr>
    <tr>
      <td>
        <code>nomad-autoscaler.runtime.total_gc_pause_ns</code>
      </td>
      <td>Cumulative nanoseconds in GC stop-the-world pauses</td>
      <td>Gauge</td>
    </tr>
    <tr>
      <td>
        <code>nomad-autoscaler.runtime.total_gc_runs</code>
      </td>
      <td>Number of completed GC cycles</td>
      <td>Gauge</td>
    </tr>
    <tr>
      <td>
        <code>nomad-autoscaler.runtime.gc_pause_ns</code>
      </td>
      <td>Number of nanoseconds to complete the last GC cycle</td>
      <td>Timer</td>
    </tr>
  </tbody>
</table>

## Policy Metrics

Policy metrics provide insights into the performance of the Nomad Autoscaler's
policy handling.

<table>
  <thead>
    <tr>
      <th>Metric</th>
      <th>Description</th>
      <th>Type</th>
      <th>Labels</th>
    </tr>
  </thead>
  <tbody>
    <tr>
      <td>
        <code>nomad-autoscaler.policy.total_num</code>
      </td>
      <td>The number of policies currently held within the autoscaler</td>
      <td>Gauge</td>
      <td></td>
    </tr>
    <tr>
      <td>
        <code>nomad-autoscaler.policy.source.error_count</code>
      </td>
      <td>Tracks the number of errors generated by the policy sources</td>
      <td>Counter</td>
      <td>policy_source</td>
    </tr>
  </tbody>
</table>

## Scaling Metrics

Scaling metrics provide insight into the performance of scaling actions as well
as overall success and failure counters.

<table>
  <thead>
    <tr>
      <th>Metric</th>
      <th>Description</th>
      <th>Type</th>
      <th>Labels</th>
    </tr>
  </thead>
  <tbody>
    <tr>
      <td>
        <code>nomad-autoscaler.scale.evaluate_ms</code>
      </td>
      <td>The time taken to evaluate the checks within a single policy</td>
      <td>Timer</td>
      <td>policy_id, target_name</td>
    </tr>
    <tr>
      <td>
        <code>nomad-autoscaler.scale.invoke_ms</code>
      </td>
      <td>The time taken to invoke scaling based on the scaling evaluations</td>
      <td>Timer</td>
      <td>policy_id, target_name</td>
    </tr>
    <tr>
      <td>
        <code>nomad-autoscaler.scale.invoke.success_count</code>
      </td>
      <td>Tracks the number of successful scaling actions triggered</td>
      <td>Counter</td>
      <td>policy_id, target_name</td>
    </tr>
    <tr>
      <td>
        <code>nomad-autoscaler.scale.invoke.error_count</code>
      </td>
      <td>Tracks the number of unsuccessful scaling actions triggered</td>
      <td>Counter</td>
      <td>policy_id, target_name</td>
    </tr>
  </tbody>
</table>

## Plugin Metrics

Plugin metrics provide insight into the performance of Nomad Autoscaler plugins
and help identify potential bottle necks or latency issues.

<table>
  <thead>
    <tr>
      <th>Metric</th>
      <th>Description</th>
      <th>Type</th>
      <th>Labels</th>
    </tr>
  </thead>
  <tbody>
    <tr>
      <td>
        <code>nomad-autoscaler.plugin.manager.access_ms</code>
      </td>
      <td>The time taken to dispense a plugin</td>
      <td>Timer</td>
      <td></td>
    </tr>
    <tr>
      <td>
        <code>nomad-autoscaler.target.status.invoke_ms</code>
      </td>
      <td>The time taken to perform the target plugin status call</td>
      <td>Timer</td>
      <td>policy_id, plugin_name</td>
    </tr>
    <tr>
      <td>
        <code>nomad-autoscaler.target.scale.invoke_ms</code>
      </td>
      <td>The time taken to perform the target plugin scale call</td>
      <td>Timer</td>
      <td>policy_id, plugin_name</td>
    </tr>
    <tr>
      <td>
        <code>nomad-autoscaler.apm.query.invoke_ms</code>
      </td>
      <td>The time taken to perform the APM plugin query call</td>
      <td>Timer</td>
      <td>policy_id, plugin_name</td>
    </tr>
    <tr>
      <td>
        <code>nomad-autoscaler.strategy.run.invoke_ms</code>
      </td>
      <td>The time taken to perform the strategy plugin run call</td>
      <td>Timer</td>
      <td>policy_id, plugin_name</td>
    </tr>
  </tbody>
</table>

[agent_telemetry_config]: /nomad/tools/autoscaling/agent#telemetry-block
